Wednesday, April 17, 2013

Symmetry in Games

As a part of the MochiPets project, I have been rapidly prototyping mini-games. This weeks game was Flip Puzzle, a game in which players flip a 3x3 area of tiles on a grid so that it will match the answer key. The core mechanic essentially being that the player needs to find the single (or multiple at higher levels) answer tile to flip that will cause the two grids to match.

I put together a couple different patters for grids spanning from 3x3 to 5x5, using the size of the grid and the number of clicks to determine difficulty. However, during play testing, I discovered something very interesting and unexpected. The symmetry of the puzzle was also a key factor in determining a puzzle's difficulty. Amongst the designed puzzles, there were puzzles with no symmetry, bilateral symmetry, and quadrilateral symmetry. Quadrilateral was least difficult, bilateral harder, and asymmetrical was the most difficult.

Once this realization came to light, it actually made a lot of sense. Our brains are designed to read patterns, and when something breaks that pattern a red flag goes off in our heads. By breaking the grids up into quadrants based on symmetry, we are easily able to distinguish which quadrant is the most problematic.

In the example above, you can clearly see that the bottom left quadrant is the most incorrect in comparison to the answer key. In fact, it is the exact inverse, so we can be reasonably sure that the tile we want to click is one of those four (it's the second column, third row ;) ). Because of this discovery, I divided the puzzles in each grid size into bins by symmetry and added this consideration to the puzzle generation algorithm.

This was a very useful discovery, especially for puzzle games! When making a game that involves patterns of any sort, whether it's pieces of a puzzle or ships flying at you, it's worth considering the symmetry of your design!